Addison c



(No Model) A. C. RAND.

STEAM ROCK DRILL.

No. 328,612. Patented Oct. 20, 1885.

N, PETERS Plwurmmgmpiwr. washmgwn. D C.

Unire STATES ADDISON C. RAND, OF NEV YORK, N. Y.

STEAM ROCK-omLL.

SPECIFICATION forming part of Letters Patent No. 328,612, dated October 20, 1885.

Application filed February 11, 1885. Serial No. 155,612. (No model.)

T0 all whom, it may concern,.-

Be it known that l, ADDISON C. RAND, of the city of New York, in the county and State of New York, and a citizen of the United States of America, have invented a new and useful Improvement in Steam Rock-Drills, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof, in which- Figure l is a side elevation of a rock-drill containing my invention. Fig. 2 is a vertical longitudinal central section of the same. Fig. 3 is a plan or top face view of the cylinder, showing the seat of the valve-chest. Fig. 4 is a cross-section of the same on lline 1/ y, Fig.

2. Fig. 5 is an under face view of the valvechest. Fig. 6 is a horizontallongitudinal central section of said valve-chest and its ports. Figs. 7 and 8 show modifications of the valve and its steam-ports, particularly described hereinafter; and Fig. 9is across-section of the drill on line z z, Fig. 2.

My invention relates to that class of steam rock-drills (I use the word steam 7 here to include all analogous agents, compressed air, and other gases) in which the valve governing the inlet and exhaust ports of the cylinders is moved, not by any mechanical device-such as a cam or lever-but by steam, the ports of which are governed bythe main piston; and it relates to that variety of this class of drills in which there is a continuous communication established between the steam-supply source and the two opposite ends of the valve and valve-chest, the shifting of the valve being accomplished by the alternate exhaust ofthe steam from the opposite ends of the valvechest.

In this class of drills to the extent that steam is introduced before the piston reaches the limit of its stroke is the force of the blow struck lessened by the cushioning of the piston on the steam.

The object of my invention is to lessen or obviate this cushioning, and while securing in any event the introduction of steam to effect the return of the piston after its shortest working-Stroke to prevent the introduction of steam and the consequent cushioning of the piston when longer working-strokes are made. This object I attain by constricting the exhaustpassage from the upper end ofthe valve-chest to so limit the rate of the exhaust for shifting the valve to admit steam to the cylinder to effect the return-stroke of the piston that there will necessarily occur,between the'opening of said exhaust-passage at the end of the shortest practical working-stroke of the piston and the actual shifting of the valve to open the inlet-passage to the lower end of the main cylinder, a determinate delay,'for the purpose of allowing the said piston to complete longer strokes by the time said passage is opened.

The same object is accomplished by the fol-l lowing equivalent arrangement: by constricting the inlet-passage to the lower end of the valve-chest, or both the said exhaust and inlet passages may be constricted.

By the invention described in Letters Patent No. 295,002, dated March 11,1881, issued to F. A. Halsey, the same general object as above set forth is accomplished; but the principle is there applied to a drill of somewhat different construction from the onc herein described.

I will now proceed to describe a steam rockdrill embodying my present invention.

Referring to the drawings, A is the main cylinder, and B is the piston adapted to reciprocate therein. This piston is elongated in form, and has a circumferential chamber, C. The drill-stock D extends from the lower end of said piston through a stuffing-box, in the usual way.

E is the valve-chest, and F the valve fitted to reciprocate therein on a rod, G, which passes through the heads of the valve-chest, and serves to hold the valve centrally in the chest. This valve-chest is mounted on and secured to the side of the cylinder, as shown. The valve F is cylindrical in form, having projecting flanges a a at its ends, thus forming an annular chamber, f, in the middle portion ofthe valve. That portion of this valve which is nearest the main cylinder has a projection formed upon its central portion,which is provided with a cavity, b, which opens into the exhaust-passage b in the wall ofthe main cyl-l inder. This cavity also in operation registers alternately with the passages d and d', which are both induction and cduction passages to the opposite ends of the main cylinder,where- IOO ' ofthe piston cross from one end of the valvechest to the other, so that the exhaust from the upper end of the valve-chest is through the porte, and from thelower end through the port e. I call the lower ends of the valvechest and cylinder those looking in the direction ofthe drill D.

The flanges a a do not t tightly in the valve-chest, a small space being left between them and it to permit the passage of steam from the chamber f to the ends of the valve.

The general construction and operation of this drill are well known, and a particular description is not deemed necessary. I will only describe the peculiarity which constitutes my present invention.

As will be understood, the chamber f being in constant communication with the steam supply, the steam will be introduced into the main cylinder to operate its piston by the shifting of the valve F alternately from one end to the other of the valve-chest, so that when the valve is thrown upward, and c registers with d, the steam is introduced into the lower end of the main cylinder. At the same time the cavity b registers with the passage d', and the exhaust takes place from the upper end of the cylinder, and the operation is reversed when the valve is thrown to the opposite end. l

My present invention relates only to the shifting ofthe said valve. As shown in the drawings, Fig. 2, the exhaust-port e is con.

stricted relatively to the size of the port e', so that the steam is exhausted slower or more gradually from the upper end of the valvechest than from the lower. This port e is to be sufficiently constricted, having reference to the weight and inertia of the valve, so that there will be a determinate delay between the opening of said port at the termination of the shortest practical working-stroke of the piston and fthe actual shifting of the valve to open the inlet-port to the lower end of the cylinder, for the purposeof allowing the'said piston to complete longer strokes by the time said inlet-port is opened. This constriction in the exhaust-port leading from the upper end of the valve-chest may be made at any point in the said exhaust-passage. The rule Jor proportioning ofthe size of this'constricted port is more fully explained in the patent above referred to, issued March 1l, 1884, to which reference is here made.

In place of constricting the exhaust-port e, as described, the opening between the ilange a on the lower end of the valve and the side of the valve-chest may be constricted relatively to the corresponding opening at the other end of the valve, as shown in Fig. 7; or the auges may make substantially steam -tight joints with the cylinder, and small apertures may be made through the fiianges between the chamberf and the ends of the valve-chest, the said ape-rturein the flange at the lower end of the valve being made relatively smaller than that in the opposite end, as shown in Fig. 8.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. In a steam rock-drill in which the valve controlling the steam-passages to the main cylinder is moved by steam under continuous and uninterrupted pressure on the valve, and in which the valve is shifted while this continuous pressureis maintained by alternately exhausting the steam from oppositeends of the valve-chest, the combination,with the described main cylinder and elongated piston provided with the annular chamber C, and the described induction and eduction passages to the main cylinder andthe described valvech'est E and valve F, provided with the tlanges a anda', annular chamber f, and cavityV b, the steam-passages establishing constant communication between the said chamber fand the steam-supply source, of steam-exhaust passages leading from the opposite ends of the valve-chest to the annular chamber C, the ex- .haust-passage leading from the upper end of the said valve-chest being constricted in size relatively to the other of said exhaust-passages, as and for the purpose described.

2. In a steam rock-drill in which the valve controlling the steam-passages to the main` cylinder is moved by steam under continuous- IOO and uninterrupted pressure on the valve, and

in which the valve is shifted while this continuous pressure is maintained by alternately exhausting the steam from opposite ends of the valve-chest,l the combination,with the described main cylinder and elongated piston provided with the annular chamber C, and the described induction and eduction passages to the main cylinder, and the described valvechest E and valve F, provided with the flanges a and a', annular chamber f, and cavity b, the steam-passages establishing constant communication between the said ohamberf and the steam-supply source, of the exhaust-passages e and e', leading, respectively, from opposite ends of the valve-chest to the annular chamber C, the opening between the iiange upon the lower end of said valveF and the wall of the valvechest being less than the corresponding open- IIS exhausting the steam from opposite ends of supplysource7 ofthe exhaustpassages e and e', the valve-chest, the combination,with the deleading, respectively, from opposite ends of scribed main cylinder and elongated piston the valve-chest to the annular chamber C, and provided With the annular chamber C, and the the holes in the flanges a and a', that in the 5 described induction and eduction passages to flange a being smaller than that in the flange I5 the main cylinder, and the described valvec, as and for the purpose described.

chest E and valve F, provided with the flanges ADDISON C. RAND. aiand a, annular chamber f, and cavity b, the Vitnesses: steam-passages establishing constant conirnu- A. G. N. VERMILYA,

1o nication between the chamber fand the steam- HENRY EICHLING. 

